Stacking effect of self-organized In 0.15Ga 0.85As quantum wires grown on (7 7 5)B-oriented GaAs substrates by molecular beam epitaxy

Abstract

We have investigated barrier width dependence of stacked InGaAs quantum wires, which were naturally formed in a thin InGaAs/AlAs quantum well (QW) with a corrugated AlAs/InGaAs upper interface (a lateral period of about 30 nm and a vertical amplitude of about 1.5 nm) and a flat InGaAs/AlAs lower interface. Stacked InGaAs quantum wires (QWRs) separated by a thin AlAs barrier ( L b=0.5,1,2 and 3 nm) were grown on the (7 7 5)B-oriented GaAs substrate by molecular beam epitaxy (MBE). The photoluminescence (PL) peaks from stacked (7 7 5)B InGaAs QWRs with L b=0.5 nm were observed at 65 meV lower than that of previous (7 7 5)B InGaAs QWR structures. The polarization degree [ P≡( I ∥− I ⊥)/( I ∥− I ⊥)] of PL at 13 K from the (7 7 5)B stacked QWRs with L b =0.5 nm is 0.18, which is as large as that of for L b =3 nm. The largest PL intensity was shown for the samples with L b=0.5 nm. These results indicate that a stack of (7 7 5)B InGaAs QWRs with very thin AlAs barrier layers ( L b=0.5 nm) are suitable for laser applications due to their larger effective band offset and high polarization degree of PL.